I am not against your point of view.
In USA is experimental category still popular and you need PPL to fly experimental. In Czech Republic is situation different - we have only very few experimental airplanes and is not easy to register new plane as experimental. So I have to follow UL-2 rules issued by LAA. They give me a lot of freedom (MTOM 600 kg, stall speed 83 km/h, no limit for engine power etc.) but also some limitations. I cannot discuss with inspector that in case on failure "
...is hard for me to imagine that anyone is really going to have much issue controlling it". I just have to show that opposite motor will automatically stop as well.
Before we start to design airplane we have to follow rules and we have to look also to other EU countries what they allow in UL category. So finally I am facing even more limitations. UL pilot license is affordable = very popular.
Following my "keep it simple" rule makes my sitution easier.
Unfortunatelly it also means less dream designs....
So.... yes, you are right that two small electric motors + one IC engine is OK. You are also right that even assyymetric thrust situation should be handled by pilot with standard skills. I pragmatically say - for tandem propulsion configuration would be easier to get permit to fly
But here on HBA we can dream even about "oscillating thrusters" or "multi motor propulsion". I have no problem with that